When a frontal collision or crash occurs, two things happen, depending on the severity of the crash, namely, (1) the driver moves forwardly against the steering wheel, and (2) the powertrain impacts rearward vehicle portions.
When the driver moves forwardly, the steering wheel is normally at an angle such that his chest will strike the steering wheel. In many late model vehicles, the steering wheel is equipped with an air bag which deploys upon impact and cushions the reaction force of the driver's chest against the steering wheel. However, as the powertrain impacts rearward vehicle portions, it may contact the steering column intermediate shaft and rotate the steering column to a greater angle so that the air bag does not deploy against the driver's chest, as intended, but rather higher up and at an undesirable angle. At this greater angle, the steering wheel and air bag do not provide the driver with the same level of safety protection.
What is needed is a device to absorb the energy of the powertrain and occupant rearward vehicle portions so that the angle of the steering column will not be influenced.
More specifically, the energy absorbing device of this invention comprises a bracket in the form of a generally box-shaped frame formed with openings in the side panels and in a transverse panel which extends between the side panels. These openings define elongated upper and lower struts. The bracket is positioned above the steering column and has the front end portion secured to the vehicle support structure and a rear end portion operatively connected to the steering column. The bracket is adequately stiff to support the steering column, yet bendable, such that it is capable of controllable deformation when the powertrain contacts the rearward vehicle portions in a frontal collision. In this way, the force of the powertrain and occupant is gradually dissipated in a controlled manner so that the angle of the steering column is not materially changed, and the intended air bag performance is preserved.
Preferably, one or more of the struts is formed with flex points which initiate controllable deformation under the impact of the rearward vehicle portions with the powertrain. Preferably, the lower struts have less resistance to deformation than the upper struts and therefore deform more readily than the upper struts. In a more severe crash, both the upper and lower struts will deform and thus gradually absorb energy.
Preferably, the energy absorbing device includes a second bracket for securing the steering column to the first bracket. Fasteners form a releasable connection between the two brackets, so that the second bracket can be removed, permitting better access to the first bracket which can then be secured to the vehicle support structure without interference from the second bracket.
One object of this invention is to provide an energy absorbing device having the foregoing features.
Another object is to provide an energy absorbing device which is composed of a relatively few simple parts, can be easily and inexpensively manufactured, and is highly effective in controlling the rotational and longitudinal movement of the steering column in a collision.
Other objects, features, and advantages of this invention will become more apparent from the following description and claims, especially when considered with the accompanying drawings.